— The father of the American teen who was allegedly beaten by Israeli police last week has filed a formal complaint against authorities there, advocates said Tuesday, and relatives in Maryland demanded that he be allowed to return to the United States.

Fifteen-year-old Tariq Abu Khdeir was visiting family in East Jerusalem when a cousin was abducted and burned to death last Wednesday. The killing came in apparent retaliation for the abduction and deaths of three Israeli teens last month.

Tariq, who was born in Baltimore and still has many relatives in Maryland, was in the village of Shuafat last Thursday when protesters clashed with police before his cousin's funeral. He says he was watching, not participating, when he was detained by police.

Video footage has surfaced of two police officers pummeling a masked youth. Photographs of Tariq taken after the alleged incident show him with two black eyes, a bloodied nose and a badly swollen mouth.

The U.S. State Department has expressed "shock" at the beating and called for a quick, transparent and credible investigation.

The Israeli Embassy in Washington said the nation's Justice Ministry has launched a probe.

"Excessive force will not be tolerated, and Israel's professional and independent judiciary will of course investigate this matter thoroughly," the embassy said in a statement.

"It should also be noted," the embassy said, "that this teenager was no innocent bystander. He was taking part in a mass demonstration attacking policemen. He was masked, along with a knife-carrying group of six who threw petrol-bombs and Molotov cocktails at policemen."

Tariq told reporters after his release Sunday that he had not fought with police.

Family members in Maryland, speaking Tuesday at the Washington office of the Council on American-Islamic Relations, said Tariq is nonpolitical and nonviolent. They say he has not been charged with any offense.

Maria Baroody, an Aberdeen Middle School teacher who is married to one of Tariq's cousins, said he was simply watching protesters clash with police from the courtyard of a relative's house.

Baroody said Tariq was covering his face with a keffiyeh, a scarf associated with Palestinian nationalism, to protect against tear gas.

Tariq was released on Sunday but remains in Israel under house arrest for the duration of his stay. Family members demanded that he be allowed to return to the United States immediately.

"We want to bring Tariq home so he can get medical attention," said Hakeim Abu Khdeir, a cousin in Baltimore. "We want justice. We want those who beat a minor to face time for that."

Tariq attended John Ruhrah Elementary School in Baltimore. He moved with his parents to Florida when he was about 12.

Salisbury University has suspended its Phi Beta Sigma fraternity chapter for hazing, after members were reported to have hit pledges with paddles and held forced workouts at an off-campus house, school officials said.